The transcription factor NF-E2 and the gene encoding PRV-1 are overexpressed in patients with[unreadable] polycythemia vera (PV). The recent description of a Jak2V617F mutation in PV patients raises the question[unreadable] whether this allele exerts its effect on the malignant clone in part through inducing NF-E2 expression. NF-E2[unreadable] is a promising candidate in the pathophysiology of PV for several reasons:[unreadable] NF-E2 is overexpressed in stem cells as well as in all three cell lineages affected in PV. In murine cells NFE2[unreadable] overexpression leads to Epo-independent growth and differentiation. NF-E2 may thus play a pivotal role[unreadable] in causing the erythrocytosis of PV. However, both the molecular mechanism leading to NF-E2[unreadable] overexpression and its effect on human hematopoiesis are not known. In addition, the cause of PRV-1[unreadable] overexpression remains unclear. Therefore, it is the aim of this project to investigate the cause of NF-E2[unreadable] and PRV-1 overexpression in PV and the effect of NF-E2 overexpression in hematopoietic cells.[unreadable] Based on the following hypotheses, the specific aims of this project are therefore:[unreadable] 1. Hypothesis: NF-E2 is required for the Epo-independent growth of PV cells or its overexpression[unreadable] modulates hematopoietic differentiation. Specific Aim: To modulate NF-E2 expression via siRNA knock down[unreadable] and retroviral or lentiviral transduction and examine the consequences on Epo-dependent and -independent[unreadable] growth in vitro.[unreadable] 2. Hypothesis: NF-E2 and PRV-1 overexpression in PV are mediated by the Jak2V617F allele Specific Aim:[unreadable] To introduce Jak2 wt and V617F alleles in vivo and in vitro and examine the effects on NF-E2 and PRV-1[unreadable] expression in various models.[unreadable] 3. Hypothesis: NF-E2 and PRV-1 overexpression result from aberrant transcriptional activation Specific Aim:[unreadable] To characterize protein/DNA interaction on the NF-E2 and PRV-1 promoters in PV and healthy control cells[unreadable] to determine aberrantly activated transcription factors.[unreadable] Public Health Implications: By leading to a better understanding of the molecular changes that lead to the[unreadable] development of PV, this project will point out molecules against which new drugs for treatment can be[unreadable] developed.